In the related art, as a technique to detect the travel direction of a target, there have been proposed a guest count detection apparatus for measuring the number of guests entering/exiting a department store, an exhibit and the like through its entrance/exit (for example, refer to JP-A-05-54142) The guest count detection apparatus disclosed in JP-A-05-54142 binarizes the difference between a first captured image and a second captured image, performs fixed differentiation to compress the number of pixels, and measure and determine the number and positions of the obtained differential pixels, thereby calculating the travel direction and number of target persons.
However, the related art technique has a problem that the amount of information is huge since the difference between all pixels in the first image and the second image in order to detect the travel direction of persons.
The invention has been accomplished in view of the related art problem and has as an object to provide a target travel direction detecting method capable of detecting the travel direction of a target by using a small amount of information.